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DEPARTMENT OF TRANSPORTATION UNIFORM
TIRE QUALITY GRADES
The following tire grading categories were estab-
lished by the National Highway Traffic Safety Ad-
ministration. The specific grade rating assigned by
the tire’s manufacturer in each category is shown on
the sidewall of the tires on your vehicle.
All passenger vehicle tires must conform to Federal
safety requirements in addition to these grades.
Treadwear
The Treadwear grade is a comparative rating, based
on the wear rate of the tire when tested under
controlled conditions on a specified government test
course. For example, a tire graded 150 would wear
one and one-half times as well on the government
course as a tire graded 100. The relative performance
of tires depends upon the actual conditions of their
use, however, and may depart significantly from the
norm due to variations in driving habits, service
practices, and differences in road characteristics and
climate.
Traction Grades
The Traction grades, from highest to lowest, are AA,
A, B, and C. These grades represent the tire’s ability
to stop on wet pavement, as measured under con-
trolled conditions on specified government test sur-
faces of asphalt and concrete. A tire marked C may
have poor traction performance.
WARNING!
The traction grade assigned to this tire is based
on straight-ahead braking traction tests, and does
not include acceleration, cornering, hydroplan-
ing, or peak traction characteristics.
Temperature Grades
The temperature grades are A (the highest), B, and C,
representing the tire’s resistance to the generation of
heat and its ability to dissipate heat, when tested
under controlled conditions on a specified indoor
laboratory test wheel. Sustained high temperature
can cause the material of the tire to degenerate and
reduce tire life, and excessive temperature can lead
to sudden tire failure. The grade C corresponds to a
level of performance, which all passenger vehicle
234 STARTING AND OPERATING
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